1. Field of the Invention
The present invention relates to oral care compositions exhibiting improved antiplaque activity on dental tissue of noncationic antibacterial compounds.
2. The Prior Art
Intraoral surfaces, either soft or hard, frequently are covered by a bacterial deposit called "plaque". Such dental plaque is a soft deposit which adheres tenaciously at the points of irregularity or discontinuity on dental tissue, e.g., on rough calculus surfaces, at the gum line and the like. Plaque generally consists of about 70% by weight bacteria, with the balance comprised of host cells, food debris, proteins, polysaccharides, etc. Besides being unsightly, plaque is implicated in as a causative factor in caries and periodontitis, which together are responsible for about 95% of tooth loss.
As disclosed in U.S. Pat. No. 5,043,154 a wide variety of noncationic antibacterial agents have been suggested in the art to retard plaque formation and the oral infections and dental disease associated therewith. For example, halogenated hydroxydiphenyl ether compounds such as Triclosan are well known to the art for their antibacterial activity and have been used in oral compositions to counter plaque formation.
Although antibacterial agents such as Triclosan are highly effective, it is difficult to deliver an effective therapeutic level of such agents on dental tissue. As disclosed in U.S. Pat. No. 4,894,220, and U.S. Pat. No. 5,032,386 certain polymeric polycarboxylates, such as vinyl ether-maleic anhydride copolymers, enhance the delivery of the antiplaque agent on dental tissue, and consequently enhance the antiplaque efficacy of these agents.
Accordingly, the greater the amount of antibacterial compound delivered to infected areas of dental tissue by saliva present in the mouth the more efficacious the antiplaque effect. There is therefore a continuous interest in the art to provide means whereby nonionic antibacterial compounds contained in oral care compositions can be more efficaciously delivered to dental tissue.